Global temperature change is a gradual increase in the overall temperature of the Earth's atmosphere.
Both human activity and natural processes have contributed to this temperature increase. Examples of
human activities include the burning of fossil fuels, cement production, and agricultural activity. Examples
of natural processes include changes in incoming solar radiation and volcanic activity.
Scientists present evidence for the rise in global temperature in the form of tables, graphs, maps, and
models. For example, scientists build climate models (computer simulations of climate systems) to
explore the causes and effects of global temperature change and to predict future trends. These models
predict that the Earth’s average surface temperature will rise as greenhouse gas concentrations continue
to rise. Based on these models, scientists predict that average surface temperatures could rise by
between 2°C and 6°C by the end of the 21st century.

You are familiar with some of the factors that have contributed to the rise in global temperatures
over the past century. Think of three questions that will help you clarify your understanding of how
these factors lead to an increase in global temperatures. Consider the following when you come
up with your questions:
i. Ways in which natural processes and human activity have affected global temperature
change over the past century
ii. The influence of these processes and activities on a gradual or sudden change in global
temperature